Cats - are they a threat to a free ranging brrdy?

Just got back from shops having left the gurls out in a fenced in part of the garden.There was a small kitten looking cat loitering in the fenced off bit, sniffing at the rabbit in the run, and the chickens were sort of huddled in their ark looking slightly perturbed and shifting from foot to foot.

I made friends with the cat and unceremoniously removed it from the area, however it occurs to me there could have been a kerfuffle or perhaps even a set-to, had I not arrived when I did. Or if a bigger cat decided o have a go?

So are cats generally a threat or should we be Ok if this happens again?